A device and method for reducing the motion of an offshore engineering vessel

Abstract

The present invention discloses a device for reducing the motion of an offshore engineering ship, which includes two positioning piles that pass through both sides of the hull near the stern and are inserted into the seabed. Each positioning pile includes a pile leg, a lifting drive mechanism, and a pile shoe; the pile leg is cylindrical and two racks are symmetrically fixed on the outer surface; a pile leg flange is provided at the lower end of the pile leg; the lifting drive mechanism includes a pair of drive motors that rotate in opposite directions and a pair of gears that are respectively installed on the output shafts of the pair of drive motors and mesh with the two racks on the pile leg; a pile shoe flange is provided at the top of the pile shoe and an installation groove for accommodating the neck of the pile leg flange is opened in the center of the top surface, and four limiting grooves corresponding to the four limiting flanges on the pile leg flange are uniformly opened on the wall surface of the installation groove. The pile shoe flange and the pile leg flange are connected by bolts to integrate the pile shoe and the pile leg. The present invention also discloses a method for reducing the motion of an offshore engineering ship. The present invention can more effectively reduce the motion of the engineering ship.

Description

Technical Field

[0001] The present invention relates to a device and method for reducing the motion of an offshore engineering ship. Background Art

[0002] With the development of China's water transportation industry and offshore wind power, the construction of projects such as ports, docks, breakwaters, and offshore wind farms needs to gradually move towards the open sea. Engineering ships are prone to large six-degree-of-freedom motions under the influence of long-period swells in the open sea, resulting in difficult construction. Regarding the methods for reducing ship motion, decades of research have been carried out in the ship field, but many specific measures mainly target ships with a relatively small block coefficient, such as fin stabilizers and roll-adjusting water tanks, which are not applicable to engineering ships with a large block coefficient.

[0003] For engineering ships, the method of usually installing heaving plates on both sides of the hull is generally adopted for roll reduction. The heaving plates interact with water to generate damping and dissipate the kinetic energy of the ship's motion, thereby reducing the ship's motion response. However, due to the small density and viscosity of water, if roll reduction of an engineering ship is to be achieved, the scale of the required heaving plates is large and the number is large. At this time, the installation and use of the heaving plates will become relatively difficult. Compared with seawater, seabed silt has a larger density and viscosity. If the existing roll reduction device of an engineering ship is inserted into the silt, the motion response of the engineering ship can be greatly reduced through the interaction between the roll reduction device and the silt. However, there is currently no device for inserting into the seabed silt for ship roll reduction. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a device and method for reducing the motion of an offshore engineering ship, which can more effectively reduce the motion of the engineering ship and improve the operation performance of the offshore engineering ship.

[0005] A technical solution for achieving the purpose of the present invention is: a device for reducing the motion of an offshore engineering ship, including two positioning piles that pass through both sides of the hull near the stern and are inserted into the seabed. Among them,

[0006] Each positioning pile includes a pile leg, a lifting drive mechanism, and a pile shoe;

[0007] The pile leg is cylindrical and two racks are symmetrically fixed on the outer surface of the pile leg; a pile leg flange is provided at the lower end of the pile leg, the pile leg flange is a necked flange, and four limiting flanges are uniformly arranged on the outer peripheral surface of the neck;

[0008] The lifting drive mechanism is installed on the hull and includes a pair of drive motors and a pair of gears; the pair of drive motors rotate in opposite directions and are symmetrically installed on both sides in front of or behind the pile leg; the pair of gears are respectively installed on the output shafts of the pair of drive motors and respectively mesh with the two racks on the pile leg;

[0009] The top of the pile shoe is provided with a pile shoe flange. A mounting groove for accommodating the neck of the leg flange is formed in the center of the top surface of the pile shoe, and four limiting grooves corresponding one by one to four limiting flanges on the leg flange are evenly formed on the wall surface of the mounting groove. The pile shoe flange is connected to the leg flange through bolts, so that the pile shoe and the leg are integrated into one body.

[0010] In the above-mentioned device for reducing the motion of an offshore engineering ship, one structure of the pile shoe includes a pile shoe body with a cylindrical upper part and a conical lower part, and pile shoe insertion rods with a number that is a multiple of three and at most twelve. Six threaded insertion holes are evenly formed on the outer peripheral surface of the upper part of the pile shoe body in the same horizontal plane in the radial direction. The pile shoe insertion rod includes a threaded rod meshed and connected with the threaded insertion hole on the pile shoe body and a cylinder coaxially connected to the rear end of the threaded rod and having a diameter larger than that of the threaded rod. A threaded blind hole with a length adapted to the length of the threaded rod is coaxially formed on the rear end surface of the cylinder. Three pile shoe insertion rods are inserted into three of the threaded insertion holes of the pile shoe body at intervals; alternatively, six pile shoe insertion rods are inserted into the six threaded insertion holes of the pile shoe body one by one; alternatively, six of the nine pile shoe insertion rods are inserted into the six threaded insertion holes of the pile shoe body one by one, and the other three pile shoe insertion rods are inserted into the threaded blind holes at the rear ends of the three pile shoe insertion rods already inserted into the pile shoe body at intervals; alternatively, six of the twelve pile shoe insertion rods are inserted into the six threaded insertion holes of the pile shoe body one by one, and the other six pile shoe insertion rods are inserted into the threaded blind holes at the rear ends of the six pile shoe insertion rods already inserted into the pile shoe body one by one;

[0011] Another structure of the pile shoe only has a pile shoe body in the shape of a flat-bottomed cylinder.

[0012] Another technical solution for achieving the purpose of the present invention is: a method for reducing the motion of an offshore engineering ship, based on the device for reducing the motion of an offshore engineering ship of the present invention, and including the following steps:

[0013] Step 1, collect the environmental conditions of the construction sea area. The environmental conditions mainly include wave data, water depth parameters, and geological parameters; the geological parameters include the thickness of the silt layer and soil properties;

[0014] Step 2, first model the engineering ship using hydrodynamic performance calculation software, and then calculate the maximum motion response that the engineering ship may have in the hydrodynamic performance calculation software according to the collected wave data;

[0015] Step 3: Based on the maximum motion responses that the engineering vessel may exhibit, the water depth of the construction water area, the thickness of the silt layer, and the soil properties, select the pile shoes of the two structures, and calculate the penetration depth of the positioning piles with the optimal pile shoes; then assemble the optimal pile shoes onto the legs, and finally adjust the penetration depth of the positioning piles to the calculated required depth through the positioning pile lifting mechanism;

[0016] Step 4: Install a wave data acquisition device, a depth sounder, and a six-degree-of-freedom motion response acquisition device on the engineering vessel to collect wave data, water depth, and the six-degree-of-freedom motion response data of the vessel in real time;

[0017] Step 5: When there are significant changes in the collected wave data, water depth, and the six-degree-of-freedom motion response data of the vessel compared with the data collected in Step 1, repeat Step 3, select the pile shoes of the two structures again, and calculate the penetration depth of the positioning piles with the optimal pile shoes; then assemble the optimal pile shoes onto the legs, and then adjust the penetration depth of the positioning piles to the calculated depth through the lifting drive mechanism.

[0018] For the above method for reducing the motion of an offshore engineering vessel, when performing Step 3, select the pile shoes of the two structures based on the roll motion response equation (1) of the vessel with positioning piles, and calculate the penetration depth of the positioning piles with the optimal pile shoes:

[0019]

[0020] In Equation (1), I xx is the superposition of the moment of inertia of the vessel and the added water moment of inertia, which is related to the height of the center of gravity of the vessel, the displacement of the vessel, and the weight distribution of the vessel, and is calculated using the following formula (2):

[0021]

[0022] In Formula (2), Δ is the displacement of the vessel; g is the acceleration due to gravity; B is the beam of the vessel;

[0023] In Equation (1), is the roll angle of the vessel; is the roll angular velocity of the vessel; is the roll angular acceleration of the vessel, and is calculated using the following formula (3):

[0024]

[0025] In Formula (3), is the amplitude of the vessel's roll; ω is the frequency of the vessel's roll;

[0026] In Equation (1), B 1 is the roll damping of the vessel, which is related to the hull shape, and is calculated using the following empirical formula (4):

[0027]

[0028] In Equation (1), B 2 is the damping coefficient of the positioning pile and is calculated using the following formula (5):

[0029]

[0030] In Equation (1), Δ is the displacement of the ship, which is obtained by establishing a hull model in hydrodynamic calculation software and calculating after determining the draft of the ship;

[0031] In Equation (1), GM is the initial metacentric height of the ship, which is obtained by establishing a hull model in hydrodynamic calculation software and calculating after determining the draft of the ship;

[0032] In Equation (1), is the rolling moment caused by wave loads, which is related to the wave period and wave height and is obtained by establishing a hull model in hydrodynamic calculation software and calculating after inputting the wave period and wave height;

[0033] Substituting Equation (2), Equation (3), Equation (4) and Equation (5) into Equation (1) gives the amplitude of the ship's roll and the frequency ω of the ship's roll;

[0034] After the positioning pile is inserted into the seabed silt, the part of the positioning pile in the silt generates damping due to friction with the seabed silt. The resistance F of the seabed silt to the positioning pile D is calculated using the following formula (6):

[0035]

[0036] In Equation (6), C D is the resistance coefficient corresponding to the soil resistance and is related to the properties of the seabed silt; ρ is the saturated density of the soil; A s is the contact area between the positioning pile and the seabed silt, which is the vertical projection area of the pile shoe downward, and is related to the structural shape of the pile shoe of the positioning pile and the number of insertion rods of the pile shoe of the positioning pile; In the ship coordinate system, with the center of gravity position of the ship as the origin, the positive direction of the x-axis is along the ship length direction pointing to the bow, the positive direction of the Y-axis is along the ship width direction pointing to the port side, and the positive direction of the z-axis is upward along the draft direction. L is the distance from the bottom center of the positioning pile to the x-axis and is related to the installation position of the positioning pile, the water depth and the depth of the positioning pile in the silt;

[0037] Since the damping of the positioning pile is generated by the friction between the positioning pile and the seabed silt, the following formula (7) is obtained:

[0038]

[0039] Substitute Formula (5) and Formula (6) into Formula (7). When the contact area A between the positioning pile and the seabed silt s is determined, the distance L from the bottom center of the positioning pile to the x-axis is calculated by the above formula;

[0040] Finally, the penetration depth d of the positioning pile is calculated using the following Formula (8):

[0041]

[0042] In Formula (8), A x is the projected length of the distance from the bottom center of the positioning pile to the x-axis in the Y-axis direction, which is related to the installation position of the positioning pile; h is the vertical distance from the seabed mud surface to the center of gravity of the ship.

[0043] The offshore engineering ship motion mitigation device and method of the present invention have the following characteristics:

[0044] 1. The positioning pile adopted by the mitigation device of the present invention is connected by bolts through the pile leg flange and the pile shoe flange. Different pile shoes can be installed with one pile leg. According to the different environmental conditions of the construction sea area of the engineering ship, pile shoes with different structures can be selected, which can meet the construction requirements of different sea areas, and the operation is simple and the connection is reliable.

[0045] 2. The pile shoe insertion rod and the pile shoe body, and between the pile shoe insertion rods are connected by threads. This detachable connection structure can adjust the number of pile shoe insertion rods according to the actual geological conditions and wave conditions, which can meet the operation requirements of different sea areas and greatly improve the applicable range of the positioning pile; when the engineering ship generates six-degree-of-freedom motion responses under the action of waves, the mud-embedded part of the positioning pile moves with the engineering ship, and the mud-embedded part of the positioning pile rubs against the seabed silt to generate damping, thereby slowing down the motion of the engineering ship. By adjusting the number of pile shoe insertion rods, the damping between the mud-embedded part of the positioning pile and the seabed silt can be changed. When the penetration depth of the positioning pile is certain, the more the number of pile shoe insertion rods, the more effectively the motion of the engineering ship can be slowed down. Therefore, when the environmental conditions of the construction sea area change, the motion response of the engineering ship can be adjusted by adjusting the number of pile shoe insertion rods to achieve the purpose of slowing down the ship motion.

[0046] 3. When the positioning pile moves with the hull, the mud-embedded part of the positioning pile will rub against the seabed silt to generate damping, thereby consuming the kinetic energy of the engineering ship and further slowing down the motion of the engineering ship. Anti-rolling devices such as heave plates can only interact with water, and the density and viscosity of water are much smaller than those of the seabed silt. Therefore, to achieve the same anti-rolling effect, the size and quantity of the required positioning piles will be much smaller than those of the heave plate. Using the positioning piles inserted into the seabed silt to slow down the motion of the engineering ship will be more effective.

[0047] 4. The method for reducing the motion of an offshore engineering ship according to the present invention collects the environmental conditions during the operation of the engineering ship in real time, calculates the penetration depth required for the positioning pile based on the roll motion response equation of the ship, and then adjusts the penetration depth of the positioning pile, which not only helps to improve the adaptability of the positioning pile but also achieves the best anti-rolling effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 is a side view of the first embodiment of the device for reducing the motion of an offshore engineering ship according to the present invention;

[0049] Figure 2 is Figure 1 the bottom view of

[0050] Figure 3a is a schematic structural view of the leg in the device for reducing the motion of an offshore engineering ship according to the present invention;

[0051] Figure 3b is Figure 3a the view taken along the line A-A in

[0052] Figure 4 is a schematic structural view of the lifting drive mechanism in the device for reducing the motion of an offshore engineering ship according to the present invention;

[0053] Figure 5 is a schematic structural view of the first type of pile shoe according to the present invention;

[0054] Figure 6 is Figure 1 the enlarged view of the P part in

[0055] Figure 7a is a schematic structural view of the first combination type of the pile shoe body and the pile shoe insertion rod of the first type of pile shoe according to the present invention;

[0056] Figure 7b is a schematic structural view of the second combination type of the pile shoe body and the pile shoe insertion rod of the first type of pile shoe according to the present invention;

[0057] Figure 7c is a schematic structural view of the third combination type of the pile shoe body and the pile shoe insertion rod of the first type of pile shoe according to the present invention;

[0058] Figure 7d is a schematic structural view of the fourth combination type of the pile shoe body and the pile shoe insertion rod of the first type of pile shoe according to the present invention;

[0059] Figure 8 is a side view of the second embodiment of the device for reducing the motion of an offshore engineering ship according to the present invention;

[0060] Figure 9 is Figure 8 the bottom view of

[0061] Figure 10 It is a schematic diagram of the rolling motion response of an engineering ship under the condition that the wave incident angle is 30° without positioning piles.

[0062] Figure 11 It is a schematic diagram of the rolling motion response of an engineering ship under the condition that the wave incident angle is 30° with positioning piles having six pile shoe insertion rods and an insertion depth of 8.2 m. Specific implementation manners

[0063] The present invention will be further described below in conjunction with the accompanying drawings.

[0064] Please refer to Figures 1 to 9 , the device for reducing the motion of an offshore engineering ship of the present invention includes two positioning piles that pass through both sides of the hull 100 near the stern and are inserted into the seabed.

[0065] Each positioning pile includes a pile leg 1, a lifting drive mechanism 2, and a pile shoe 3;

[0066] The pile leg 1 is cylindrical, and two racks 11 are symmetrically fixed on the outer surface of the pile leg 1. The upper ends of the racks 11 are flush with the upper end of the pile leg 1, and the distance between the lower end of the rack 11 and the top of the pile leg 1 is 4 / 5 of the length of the pile leg 1; a pile leg flange 12 is provided at the lower end of the pile leg 1. The pile leg flange 12 is a necked flange, and four flange bolt holes 13 are evenly distributed on the edge of the pile leg flange 12, and four limit flanges 14 are evenly arranged on the outer peripheral surface of the neck of the pile leg flange 12 (see Figure 3a and Figure 3b );

[0067] The lifting drive mechanism 2 is installed on the hull 100 and includes a pair of drive motors 21 and a pair of gears 22; the pair of drive motors 23 rotate in opposite directions and are symmetrically installed on the front sides or rear sides of both sides of the pile leg 1, and the pair of gears 22 are correspondingly installed on the output shafts of the pair of drive motors 23 and correspondingly mesh with the two racks 11 on the pile leg 1 (see Figure 4 );

[0068] The pile shoe 3 has two structures.

[0069] One structure of the pile shoe includes a pile shoe body 3A and a number of pile shoe insertion rods 3B that is a multiple of three and at most twelve; wherein,

[0070] The upper part of the pile shoe body 3A is cylindrical and the lower part is conical. Six threaded jacks are evenly and radially opened on the outer peripheral surface of the upper part of the pile shoe body 3A on the same horizontal plane (see Figure 5);The top of the pile shoe body 3A is provided with a pile shoe flange 30. A mounting groove 31 for accommodating the neck of the pile leg flange 12 is formed in the center of the top surface of the pile shoe body 3A. Four limiting grooves 32 corresponding to the four limiting flanges 14 on the pile leg flange 12 are evenly formed on the wall surface of the mounting groove 31 for limiting when the pile leg 1 is connected to the pile shoe body 3A to prevent relative rotation between the pile leg 1 and the pile shoe body 3A; Four flange bolt holes 13 are also evenly formed on the edge of the pile shoe flange 30. The pile shoe flange 31 and the pile leg flange 12 are connected by four bolts 4, so that the pile shoe body 3A and the pile leg 1 are integrated. Bolt gaskets 41 are installed at both ends of each bolt 4 to prevent the bolt 4 from loosening during operation; A rubber gasket 42 is provided between the bolt 4 and the flange bolt hole 13 (see Figure 6 ). The existence of the rubber gasket 42 makes the connection between the bolt 4 and the pile leg 1 and the pile shoe body 3A tighter. At the same time, it reduces the hard friction between the bolt 4 and the pile leg 1 and the pile shoe body 3A, improves the service life of the bolt 4, and improves the safety performance of the positioning pile;

[0071] The pile shoe plug 3B includes a threaded rod 33 meshed and connected with the threaded socket on the pile shoe body 3A and a cylinder 34 coaxially connected to the rear end of the threaded rod 33 and having a diameter larger than that of the threaded rod 33. A threaded blind hole with a length adapted to the length of the threaded rod 33 is coaxially formed on the rear end face of the cylinder 34; Three pile shoe plugs 3B are inserted into three threaded sockets of the pile shoe body 3A at intervals (see Figure 7a ); Or, six pile shoe plugs 3B are inserted into six threaded sockets of the pile shoe body 3A one by one (see Figure 7b ); Or, six of the nine pile shoe plugs 3B are inserted into six threaded sockets of the pile shoe body 3A one by one, and the other three pile shoe plugs 3B are inserted into the threaded blind holes at the rear ends of the three pile shoe plugs 3A already inserted on the pile shoe body 3A at intervals (see Figure 7c ); Or, six of the twelve pile shoe plugs 3B are inserted into six threaded sockets of the pile shoe body 3A one by one, and the other six pile shoe plugs 3B are inserted into the threaded blind holes at the rear ends of the six pile shoe plugs 3B already inserted on the pile shoe body 3A one by one (see Figure 7d ). Rubber gaskets 35 are installed between the pile shoe plug 3B and the pile shoe body 3A and between the pile shoe plugs 3B to prevent the pile shoe plug 3B from loosening during the operation of the engineering ship.

[0072] Another structure of the pile shoe 3 only has a pile shoe body in the shape of a flat-bottomed cylinder (see Figure 8 and Figure 9) At the top of the pile shoe 3, there is a pile shoe flange 30. In the center of the top surface of the pile shoe 3, an installation groove 31 for accommodating the neck of the pile leg flange 12 is provided. And on the wall surface of the installation groove 31, four limiting grooves 32 corresponding to the four limiting flanges 14 on the pile leg flange 12 are evenly distributed, which are used for limiting when the pile leg 1 is connected to the pile shoe 3 to prevent relative rotation between the pile leg 1 and the pile shoe 3. Four flange bolt holes 13 are also evenly distributed at the edge of the pile shoe flange 30. The pile shoe flange 31 and the pile leg flange 12 are connected by four bolts 4, so that the pile shoe 3 and the pile leg 1 are integrated. Bolt washers 41 are installed at both ends of the bolt 4 to prevent the bolt 4 from loosening during operation. A rubber pad 42 is arranged around the bolt 4. The existence of the rubber pad 42 makes the connection between the bolt 4 and the pile leg 1 and the pile shoe 3 tighter. At the same time, it reduces the hard friction between the bolt 4 and the pile leg 1 and the pile shoe 3, improves the service life of the bolt 4, and improves the safety performance of the positioning pile.

[0073] The pile shoe of the current ship positioning pile is not replaceable and cannot be adjusted according to the change of environmental conditions, so its adaptability is low. On this basis, the present invention is improved, and a positioning pile with a replaceable pile shoe is proposed as a device for slowing down the movement of an engineering ship.

[0074] The method for slowing down the movement of an offshore engineering ship according to the present invention is based on the device for slowing down the movement of an offshore engineering ship according to the present invention.

[0075] The method for slowing down the movement of an offshore engineering ship according to the present invention includes the following steps:

[0076] Step 1: Collect the environmental conditions of the construction sea area. The environmental conditions mainly include wave data, water depth parameters, and geological parameters. The geological parameters include the thickness of the silt layer and soil properties.

[0077] Step 2: First, use hydrodynamic performance calculation software to model the engineering ship, and then calculate the maximum motion response that the engineering ship may have by using the hydrodynamic performance calculation software according to the collected wave data.

[0078] Step 3: According to the maximum motion response that the engineering ship may have, the water depth of the construction water area, the thickness of the silt layer, and the soil properties, and based on the roll motion response equation (1) of the ship with a positioning pile, select the pile shoes of two structures, and calculate the penetration depth of the positioning pile with the best pile shoe.

[0079]

[0080] In formula (1), I xx is the superposition of the moment of inertia of the ship and the added water moment of inertia, which is related to the height of the center of gravity of the ship, the displacement of the ship, and the weight distribution of the ship, and is calculated by the following formula (2):

[0081]

[0082] In formula (2), Δ is the displacement of the ship; g is the acceleration due to gravity; B is the beam of the ship;

[0083] In formula (1), is the roll angle of the ship; is the roll angular velocity of the ship; is the roll angular acceleration of the ship, and is calculated using the following formula (3):

[0084]

[0085] In formula (3), is the amplitude of the ship's roll; ω is the frequency of the ship's roll;

[0086] In formula (1), B 1 is the roll damping of the ship, which is related to the hull shape, and is calculated using the following empirical formula (4):

[0087]

[0088] In formula (1), B 2 is the damping coefficient of the positioning pile, and is calculated using the following formula (5):

[0089]

[0090] In formula (1), Δ is the displacement of the ship, which is obtained by establishing a hull model in hydrodynamic calculation software and calculating after determining the draft of the ship;

[0091] In formula (1), GM is the initial metacentric height of the ship, which is obtained by establishing a hull model in hydrodynamic calculation software and calculating after determining the draft of the ship;

[0092] In formula (1), is the roll moment caused by wave loads, which is related to the wave period and wave height, and is obtained by establishing a hull model in hydrodynamic calculation software, inputting the wave period and wave height, and then calculating the roll motion response of the ship with the positioning pile;

[0093] Substituting formula (2), formula (3), formula (4) and formula (5) into formula (1) gives the amplitude of the ship's roll and the frequency ω of the ship's roll;

[0094] After the positioning pile is inserted into the seabed silt, the part of the positioning pile inserted into the silt rubs against the seabed silt to generate damping, and the resistance F of the seabed silt to the positioning pile D is calculated using the following formula (6):

[0095]

[0096] In formula (6), C D is the resistance coefficient corresponding to the soil resistance, which is related to the characteristics of the seabed silt; ρ is the saturated density of the soil; A s is the contact area between the positioning pile and the seabed silt, that is, the vertical downward projection area of the pile shoe, which is related to the structural shape of the pile shoe of the positioning pile and the number of insertion rods of the pile shoe of the positioning pile; in the ship coordinate system, with the center of gravity position of the ship as the origin, the positive direction of the x-axis is along the ship length direction pointing to the bow, the positive direction of the Y-axis is along the ship width direction pointing to the port side, and the positive direction of the z-axis is upward along the draft direction. L is the distance from the bottom center of the positioning pile to the x-axis, which is related to the installation position of the positioning pile, the water depth, and the penetration depth of the positioning pile into the mud;

[0097] Since the damping of the positioning pile is generated by the friction between the positioning pile and the seabed silt, the following formula (7) is obtained:

[0098]

[0099] Substitute formula (5) and formula (6) into formula (7). When the contact area A between the positioning pile and the seabed silt s is determined, the distance L from the bottom center of the positioning pile to the x-axis is calculated by the above formula;

[0100] Finally, the following formula (8) is used to calculate the penetration depth d of the positioning pile:

[0101]

[0102] In formula (8), A x is the projection length of the distance from the bottom center of the positioning pile to the x-axis in the y-axis direction (ship width direction), which is related to the installation position of the positioning pile; h is the vertical distance from the seabed mud surface to the center of gravity of the ship;

[0103] Then assemble the best pile shoe onto the pile leg, and then adjust the penetration depth of the positioning pile to the calculated depth through the positioning pile lifting mechanism;

[0104] Step three, install a wave data acquisition device, a depth sounder, and a six-degree-of-freedom motion response acquisition device on the engineering ship to collect wave data, water depth, and six-degree-of-freedom motion response data of the ship in real time;

[0105] Step four, when the collected wave data, water depth, and six-degree-of-freedom motion response data of the ship change significantly compared with the data collected in step one, repeat step three, select the pile shoes of the two structures again, and calculate the penetration depth of the positioning pile with the best pile shoe; then assemble the best pile shoe onto the pile leg, and then adjust the penetration depth of the positioning pile to the calculated depth through the lifting drive mechanism.

[0106] Taking a 118-meter pile driving vessel as an example, the method for reducing the motion of an offshore engineering vessel of the invention will be described. The length of the pile driving vessel is 96m, the width is 40.5m, the molded depth is 7.8m, the draft is 4.3m, and the height of the center of gravity is 9.3m.

[0107] The method for reducing the motion of an offshore engineering vessel of the present invention includes the following steps:

[0108] Step 1: The significant wave height in the construction sea area is collected as 1.5m, the average wave period is 7s, and the average water depth is 30m; the distribution of each soil layer of the seabed silt and the soil property parameters are as follows in the table:

[0109]

[0110] Step 2: First, use hydrodynamic performance calculation software to model the engineering vessel. Since the motion response of rolling is the most dangerous during the operation of the engineering vessel, the most unfavorable condition during the construction of the engineering vessel is that the wave incident angle is 30°. Therefore, input the wave conditions into the hydrodynamic calculation software, calculate the rolling motion response of the engineering vessel when the wave incident angle is 30°, and the maximum rolling angle (absolute value) is 0.682°, as shown in Table 1 below and Figure 10 :

[0111] Table 1

[0112]

[0113] Then, based on the maximum motion response that the engineering vessel may exhibit, the water depth of the construction water area, the thickness of the silt layer, and the soil properties calculated, determine that the pile shoe of the positioning pile is a combined structure of a pile shoe body 3A and a pile shoe plug 3B, and determine the number of pile shoe plugs 3B; since during the construction of offshore wind power, the pile driving vessel needs to meet the rolling angle (The absolute value) does not exceed 0.5°, and two positioning piles are used to reduce the roll of the pile driving vessel; there are four combination forms of the pile shoe body 3A and the pile shoe insertion rod 3B of the positioning pile, namely: twelve pile shoe insertion rods 3B, nine pile shoe insertion rods 3B, six pile shoe insertion rods 3B, and three pile shoe insertion rods 3B. The vertical downward projected areas of the pile shoes in these four combination forms are different. In the ship coordinate system, with the center of gravity position of the ship as the origin, the direction along the ship length pointing to the bow is the positive direction of the x-axis, the direction along the ship width pointing to the port side is the positive direction of the Y-axis, and the direction along the draft direction upward is the positive direction of the z-axis; since the installation position of the positioning pile is fixed, the projected length Ax of the distance from the bottom center of the positioning pile to the x-axis in the y-axis direction is 10m; the water depth of the construction area is measured to be 30m, and the vertical distance h from the mud surface to the center of gravity is equal to the water depth plus the center of gravity height minus the draft. By calculation, the distance L from the bottom center of the positioning pile to the x-axis is obtained. Therefore, the required penetration depths d of the positioning piles in the four combination forms are calculated, and the calculation results are shown in Table 2 below:

[0114] Table 2

[0115]

[0116]

[0117] At this time, the pile shoes in the four combination shapes can all meet the requirement that the roll angle does not exceed 0.5° at the corresponding penetration depths d of the positioning piles, but there are still differences. Since the smaller the movement response of the engineering ship during operation is, the better, the roll angles (absolute value) not greater than 0.4° corresponding to the pile shoes in the four combination forms are calculated, and the calculation results are shown in Table 3 below and Figure 11 as follows:

[0118] Table 3

[0119]

[0120] It can be seen from the above table that when the number of pile shoe insertion rods is six and the penetration depth d of the positioning pile is 8.2m, the probability that the roll angle of the engineering ship does not exceed 0.40° at a wave incident angle of 30° is the highest, which is 0.846. Therefore, the combination form of six pile shoe insertion rods for the pile shoes of the positioning pile is the best, and the penetration depth d of the positioning pile into the mud is 8.2m.

[0121] The above embodiments are only for illustrating the present invention, rather than limiting the present invention. Those skilled in the relevant technical fields can also make various changes or modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions should also belong to the scope of the present invention and should be defined by each claim.

Claims

1. A method for reducing the motion of an offshore engineering ship, based on a device for reducing the motion of an offshore engineering ship, the device comprising two positioning piles that pass through both sides of the hull near the stern and are inserted into the seabed. Among them, each positioning pile includes a pile leg, a lifting drive mechanism, and a pile shoe; the pile leg is cylindrical and two racks are symmetrically fixed on the outer surface of the pile leg; a pile leg flange is provided at the lower end of the pile leg, the pile leg flange is a necked flange, and four limiting flanges are uniformly arranged on the outer peripheral surface of the neck; the lifting drive mechanism is installed on the hull and includes a pair of drive motors and a pair of gears; the pair of drive motors rotate in opposite directions and are symmetrically installed on both sides in front of or behind the pile leg; the pair of gears are respectively installed on the output shafts of the pair of drive motors and respectively mesh with the two racks on the pile leg; the pile shoe has two structures; one structure of the pile shoe includes a pile shoe body with a cylindrical upper part and a conical lower part, and the number of pile shoe insertion rods is a multiple of three and at most twelve; six threaded insertion holes are radially and uniformly opened on the upper outer peripheral surface of the pile shoe body on the same horizontal plane; a mounting groove for accommodating the neck of the pile leg flange is opened in the center of the top surface of the pile shoe body, and four limiting grooves corresponding to the four limiting flanges on the pile leg flange are uniformly opened on the wall surface of the mounting groove. The pile shoe flange is connected to the pile leg flange through bolts to integrate the pile shoe and the pile leg; the pile shoe insertion rod includes a threaded rod meshed and connected with the threaded insertion hole on the pile shoe body and a cylinder coaxially connected to the rear end of the threaded rod and having a diameter larger than that of the threaded rod. A threaded blind hole with a length adapted to the length of the threaded rod is coaxially opened on the rear end surface of the cylinder; three pile shoe insertion rods are inserted into three threaded insertion holes of the pile shoe body at intervals; or, six pile shoe insertion rods are respectively inserted into the six threaded insertion holes of the pile shoe body; or, six of the nine pile shoe insertion rods are respectively inserted into the six threaded insertion holes of the pile shoe body, and the other three pile shoe insertion rods are inserted into the threaded blind holes at the rear ends of the three pile shoe insertion rods already inserted on the pile shoe body at intervals; or, six of the twelve pile shoe insertion rods are respectively inserted into the six threaded insertion holes of the pile shoe body, and the other six pile shoe insertion rods are respectively inserted into the threaded blind holes at the rear ends of the six pile shoe insertion rods already inserted on the pile shoe body; the other structure of the pile shoe only has a flat-bottomed cylindrical pile shoe body; a mounting groove for accommodating the neck of the pile leg flange is opened in the center of the top surface of the pile shoe, and four limiting grooves corresponding to the four limiting flanges on the pile leg flange are uniformly opened on the wall surface of the mounting groove. The pile shoe flange is connected to the pile leg flange through bolts to integrate the pile shoe and the pile leg; It is characterized in that the method for reduction includes the following steps: Step 1, collect the environmental conditions of the construction sea area. The environmental conditions mainly include wave data, water depth parameters, and geological parameters; the geological parameters include the thickness of the silt layer and soil properties. Step 2: First, use hydrodynamic performance calculation software to model the engineering ship, and then calculate the maximum motion response that the engineering ship will exhibit in the hydrodynamic performance calculation software according to the collected wave data. Step 3: Select the pile shoes of the two structures according to the maximum motion response that the engineering ship may exhibit, the water depth of the construction water area, the thickness of the silt layer, and the soil properties, and calculate the penetration depth of the positioning pile with the best pile shoe; then assemble the best pile shoe onto the leg, and finally adjust the penetration depth of the positioning pile to the depth required by the calculation through the positioning pile lifting mechanism. Step 4: Install a wave data acquisition device, a depth sounder, and a six-degree-of-freedom motion response acquisition device on the engineering ship to collect wave data, water depth, and the six-degree-of-freedom motion response data of the ship in real time. Step 5: When the collected wave data, water depth, and the six-degree-of-freedom motion response data of the ship change significantly from the data collected in Step 1, repeat Step 3, select the pile shoes of the two structures again, and calculate the penetration depth of the positioning pile with the best pile shoe; then assemble the best pile shoe onto the leg, and then adjust the penetration depth of the positioning pile to the calculated depth through the lifting drive mechanism.

2. The method for reducing the motion of an offshore engineering ship according to claim 1, wherein, when performing Step 3, select the pile shoes of the two structures based on the roll motion response equation (1) of the ship with the positioning pile, and calculate the penetration depth of the positioning pile with the best pile shoe: In Equation (1), I xx is the sum of the moment of inertia of the ship and the moment of inertia of the added water, which is related to the height of the center of gravity of the ship, the displacement of the ship, and the weight distribution of the ship, and is calculated using the following formula (2): In formula (2), Δ is the displacement of the ship; g is the acceleration due to gravity; B is the beam of the ship; In formula (1), is the roll angle of the ship; is the roll angular velocity of the ship; is the roll angular acceleration of the ship, which is calculated using the following formula (3): In formula (3), is the amplitude of the ship's rolling; ω is the frequency of the ship's rolling; In Equation (1), B 1 is the roll damping of the ship, which is related to the hull shape and is calculated using the following empirical formula (4): In formula (1), B 2 is the damping coefficient of the positioning pile and is calculated using the following formula (5): In formula (1), Δ is the displacement of the ship, which is obtained by establishing a hull model in the hydrodynamic calculation software and calculating after determining the draft of the ship; In formula (1), GM is the initial metacentric height of the ship, which is obtained by establishing a hull model in the hydrodynamic calculation software and calculating after determining the draft of the ship; In Equation (1), is the rolling moment caused by wave loads, which is related to the wave period and wave height and is obtained by establishing a hull model in hydrodynamic calculation software and inputting the wave period and wave height for calculation; Substitute Equation (2), Equation (3), Equation (4) and Equation (5) into Equation (1) to obtain the amplitude of the ship's rolling and the frequency ω of the ship's rolling; After the positioning pile is inserted into the seabed sludge, frictional damping is generated between the part of the positioning pile inserted into the mud and the seabed sludge, and the resistance F of the seabed sludge to the positioning pile D is calculated by the following formula (6): In formula (6), C D is the resistance coefficient corresponding to the soil resistance, which is related to the characteristics of the seabed silt; ρ is the saturated density of the soil; A s is the contact area between the positioning pile and the seabed silt, that is, the vertical downward projection area of the pile shoe, which is related to the structural shape of the pile shoe of the positioning pile and the number of pile shoe insertion rods of the positioning pile; in the ship coordinate system, with the center of gravity position of the ship as the origin, the positive direction of the x-axis points to the bow along the ship length direction, the positive direction of the Y-axis points to the port side along the ship width direction, and the positive direction of the z-axis points upward along the draft direction; L is the distance from the bottom center of the positioning pile to the x-axis, which is related to the installation position of the positioning pile, the water depth and the mud penetration depth of the positioning pile; Since the damping of the positioning pile is generated by the friction between the positioning pile and the seabed silt, the following formula (7) is obtained: Substitute Equation (5) and Equation (6) into Equation (7). When the contact area A between the positioning pile and the seabed silt s is determined, the distance L from the bottom center of the positioning pile to the x-axis is calculated by the above formula; Finally, use the following formula (8) to calculate the penetration depth d of the positioning pile: In formula (8), A x is the projection length of the distance from the bottom center of the positioning pile to the x-axis in the Y-axis direction, which is related to the installation position of the positioning pile; h is the vertical distance from the seabed mud surface to the center of gravity of the ship.

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